Sounds just like mine!!! I was like you before, mine has 26000 miles. It seems to me pretty normal, got the 25000 service and they told me that she's running like a clock.
I started thinking then, after all... it's a truck, might as well just sound like one!
Perfectly normal... Enjoy...2016 with a bit under 24k miles. I noticed it about a week ago, but searching revealed mostly benign diagnoses.
However, it really doesn't sound normal to me. At, least not for an engine I am hoping will go 300k.
Oil level is fine and not particularly dirty (due at 25k).
It gets slightly quieter as it warms up.
(10 second clip of me holding my phone under the wheel wells. And its a bit dirty from yesterday, heh).
https://youtu.be/y8swxfiLIzI